Dental Health in Endurance Sports: Caries, Erosion, Training

An endurance athlete who takes the plan seriously drinks sports drinks, eats gels, breathes through the mouth during intervals and skips meals when a session gets in the way. Every one of those habits makes sense for performance — and every one of them is a risk factor for the teeth. Dental examinations of triathletes, cyclists and marathon runners consistently find more erosion, more untreated caries and more enamel defects than in comparable control groups. The insidious part: enamel does not heal. Once it is gone it does not come back, and a root canal during race preparation costs not just nerves but weeks. This article explains what exactly happens, which habits cause the damage, and how to keep your fueling without wrecking your teeth.

Why endurance athletes carry a higher dental risk

The risk does not come from a single cause but from the interaction of four factors that regularly coincide in an athlete's week.

• Frequent sugar in small doses. For teeth, the total amount of sugar matters less than the number of attacks. One piece of cake means one acid attack followed by neutralisation. Six gels over four hours mean six attacks — with no recovery phase in between.
• Acidic oral pH. Sports drinks typically sit at pH 3 to 4, cola around 2.5, lemon water even lower. Enamel starts to demineralise below a pH of about 5.5 — well above what these drinks deliver.
• Reduced saliva from mouth breathing. Most athletes breathe through the mouth under load, and saliva flow drops noticeably during hard training. Saliva is the key protective mechanism: it neutralises acid, supplies calcium and phosphate for remineralisation and washes sugar away. Remove it and every acid hit lands unopposed.
• Shifted oral flora. Studies in endurance athletes show a shift towards acid-tolerant and caries-causing bacteria. That is encouraged by poorer oral hygiene in high-load phases — someone getting up at five in the morning for a long run brushes less often than in a quiet week.

Add factors that are not obviously dental: stomach acid from gastro-oesophageal reflux during hard sessions, chlorinated pool water with frequent swim training, and eating behaviour with many small snacks, as is standard in carbohydrate periodisation. If you want to understand how training load interacts with recovery systems overall, the concept is explained in TSS — training stress score.

What sports drinks, gels and bars actually do

The numbers are clear: marathon runners take in up to 60 to 90 grams of carbohydrate per hour, an Ironman burns through 8 to 12 gels, a gran fondo 6 to 10. With sugar every 20 to 30 minutes, the mouth stays acidic for hours — precisely when saliva flow is low because of the exercise itself. For teeth that means demineralisation without a neutralising phase.

On top of that comes erosion, damage independent of caries. Erosion is the chemical dissolution of enamel without bacterial involvement: sports drinks sit at pH 3 to 4, and citric acid is a particularly problematic ingredient because it also binds calcium and thus inhibits remineralisation. Repeated acid contact with low saliva flow leads to enamel loss on the chewing surfaces — first as a loss of gloss, later as translucent tooth edges and sensitivity to cold. Studies in triathletes and cyclists find erosive defects in roughly 30 to 40 percent of athletes, clearly more than in a comparison group without regular sports drinks.

The important distinction: the sports drink itself is not the problem, the pattern of intake is. Someone who drinks it only during training has a bounded window and completely normal conditions the rest of the day. Someone who sips an iso bottle all day — many cyclists keep one on the desk — creates six to eight acid attacks daily from morning to night. Two of the most effective countermeasures are therefore free: keep the sports drink for training and drink water the rest of the day. How to match your drink to sweat loss is covered in hydration for running, and a less acidic homemade recipe is in homemade sports drink.

The practical protection rules in training

The good news: you can keep almost everything and still halve the risk. These rules come from sports dentistry and barely change your training routine.

• Swallow the drink instead of holding it. Many athletes unconsciously swish the drink around the mouth, which multiplies acid exposure. Swallow directly, and chase gels with water — that dilutes the sugar solution and rinses residue off the tooth surfaces.
• Rinse with water, don't brush. After the session, first neutralise with plain water or a fluoride rinse. Brushing is right — but only 30 minutes later, because softened enamel is otherwise worn away mechanically.
• Use fluoride consistently. Fluoride is the single most effective protective factor: it speeds remineralisation and makes enamel more acid-resistant. For athletes with a high sugar frequency, fluoride toothpaste twice a day is the baseline; a high-dose fluoride rinse or gel once or twice a week can be a sensible addition. Dose and product belong in the hands of your dentist — fluoride overdosing in children is not harmless.
• Xylitol between meals. Xylitol inhibits caries bacteria and stimulates saliva flow, exactly the two mechanisms missing in a training week. Xylitol gum after a session is an easy addition; during hard training, chewing interferes with breathing, so keep it for easy runs and the rest of the day.
• Calcium-containing snacks. Cheese, unsweetened yoghurt or milk after a session neutralise acid and supply calcium and phosphate for remineralisation. A piece of cheese after a gel-heavy marathon is dentally a sensible snack — and it delivers protein too, see protein for endurance athletes.
• Test a lower-sugar drink mix. Many athletes tolerate a lower-concentration solution with the same sodium intake and end up with less sugar in the mouth. What matters is whether hourly carbohydrate intake still matches the workload — details in carb periodization and high-carb fueling.
• Oral hygiene in block weeks too. Brush twice daily, floss once, no matter how early the session starts. In heavy training blocks oral care is often the first habit to go — exactly when sugar intake and mouth breathing peak.

Enamel is irreversible — what that means for planning

The crucial difference between dental problems and other sports injuries is the absence of regeneration. A muscle gets stronger within weeks, a tendon consolidates over months, a bone heals in weeks. Enamel is not rebuilt. An erosive defect or a caries lesion reaching the pulp is permanent and requires a filling, root canal or crown — treatments that take several appointments and often a month of training plan in the middle of race preparation.

In training planning that means: dentist appointments belong in the preparation phase, not in the final weeks before a race. Anyone needing a filling should have it done at least six to eight weeks before the goal race, so any sensitivity is gone before the start and no emergency arises in race week. There is a further consideration for overall dental health: an untreated tooth is a chronic inflammatory focus that burdens recovery and the immune system. In phases with high training volume that matters — if you are already working near your limit, you do not want an extra inflammatory stimulus in the body. Fundamentals on recovery and load management are in recovery in endurance sports.

Dental protection in practice: the training and race sequence

From those rules you can build a simple sequence that costs no time:

• Before the session: brushing is fine — but not immediately before acidic drinks. Brushing right before a run and then drinking iso abrades enamel. Half an hour of separation is the simple fix.
• During the session: swallow the drink, chase gels with water, choose a more tooth-friendly drink for sessions over 90 minutes. If the session is long and sugar intake is high, a sugar-free part of the bottle plus gels for the intensity blocks can be a sensible split.
• Immediately after: water or a fluoride rinse, no brushing. Xylitol gum if available. A calcium-containing snack after long races.
• 30 minutes later: brush with fluoride toothpaste, floss. Ideally not straight after a meal high in sugar or acid.
• Across the year: two check-ups, one professional fluoride application, existing fillings checked before the season.

One special case deserves a mention: reflux. Anyone who feels stomach acid rising during hard sessions or after large meals carries an extra erosion risk, because stomach acid is far more acidic than any sports drink. Frequent belching during long sessions, which many dismiss as a normal side effect, should therefore be investigated — not only from a dental perspective. Carbohydrate amount, timing and gut tolerance are closely linked; how to train that is covered in gut training.

Common mistakes

A few habits show up again and again in practice and are unnecessarily harmful:

• Sports drink as an all-day drink. The bottle stays on the desk and the sports drink is sipped over eight hours. That cancels the advantage of a bounded window and adds up to 20 or more acid attacks per day. Sports drink belongs to training, water to the rest of the day.
• Brushing as a substitute for neutralising. Brushing hard right after a run to "get the sugar off" is exactly wrong: the softened enamel gets scrubbed away. Water and time work better than pressure and bristles.
• Citric acid in homemade drinks. Homemade sports drinks are often flavoured with lemon juice or citric acid. Citric acid is dentally problematic because of its calcium binding. If you mix your own — see homemade sports drink — keep the acid content low.
• Mouth breathing with no nasal share. Breathing purely through the mouth leaves the mucosa dry and saliva low. Keeping nasal breathing for as long as possible protects the teeth too — and lowers breathing frequency. More in nasal breathing while running.
• Race seasons without check-ups. Only seeing a dentist once it hurts. Caries does not hurt for a long time, and erosion even later. Damage discovered during race preparation costs time you no longer have.

Frequently asked questions